Wearable absorbent articles, such as diapers, sanitary towels, incontinence garments, medical dressings and the like, have wide-spread utility in both domestic and institutional settings for such purposes as the care of infants, the management of menstrual discharge, the management of bodily efflux or exudate and the management of incontinence. However, a known problem associated with the use of absorbent articles is that the articles have a finite capacity for absorption which, if exceeded, will cause the absorbent article to become ineffective, e.g., to leak, or at least to fail to absorb further.
Therefore, users of such articles, or their carers, must predict when an absorbent article is nearing its absorbent capacity and must then take steps to replace the article before capacity is reached. In situations where there are many users of such absorbent articles with relatively fewer carers, such as in institutional settings, the management of the capacity of the various absorbent articles in use becomes a significant administrative burden.
It can be very difficult for a user or carer to accurately predict or determine the state of an absorbent article, in terms both of utilised absorbent capacity and the need for the article to be replaced. Even where the absorbent demands on the article are reasonably predictable, a period of record-keeping and experimentation is required before a pattern may be established and appropriate absorbent articles may be provided.
Systems which are able to alert the user or carer to saturation or impending saturation of the absorbent article are therefore of benefit. Such systems may take the form of wetness sensors for detecting wetness within the absorbent article. The wetness sensors may use a conductor arrangement provided in the wearable absorbent article for detecting wetness by measuring the resistance between different conductors of the conductor arrangement. In this way, wetness sensors can be capable of determining both the amount of wetness and the location where the wetness event has occurred in the absorbent article.
One approach to an absorbent article containing a wetness sensor is described in WO 2012/084987.
However, when using such wetness sensors and conductor arrangements for wetness detection, the resistances of the conductors may significantly contribute to the measured resistance, especially when conductors of relatively small cross-sectional area are desired. Hence, the accuracy of the measurement, in terms of both the wetness amount and the location of the wetness event, is considerably reduced, in particular, for the case of conductors with different lengths from each other.
Hence, there remains a need for a wearable absorbent article that allows for the detection of wetness at one or more locations within the absorbent article, in particular, at one or more locations within an absorbent core of the absorbent article, with a high degree of accuracy.